The present invention relates generally to a system including an arrangement for tracking the position of a boring tool and/or one or more buried lines within a region and, more particularly, to an arrangement for using certain characteristics of a dipole locating signal emanated from the boring tool and/or certain characteristics of a locating signal emanated from the buried lines to provide indications as to the locations of the boring tool and/or the in-ground lines.
The installation of utility lines underground using horizontal directional drilling equipment is increasingly popular for reasons including elimination of the need to dig a trench. A number of prior art approaches are available for the purpose of tracking the position of the boring tool within a region using a dipole locating signal that is transmitted from the boring tool. As one example, see U.S. Pat. No. 5,633,589 entitled DEVICE AND METHOD FOR LOCATING AN INGROUND OBJECT AND HOUSING FORMING PART OF SAID DEVICE (hereinafter the ""589 patent) which is commonly assigned with the present application and which is incorporated herein by reference. The ""589 patent, like other prior art approaches, utilizes a portable locating device to detect the locating signal for use in providing positional indications to an operator.
While the ""589 patent holds a position representing a significant advance in the field of boring tool locating and is, in fact, highly accurate and effective, it is submitted that there is room for additional improvement. In particular, at least a minimum degree of skill is required on behalf of an operator to obtain locating results that are precise within some degree of tolerance. This skill requires, for example, some advance awareness and/or training regarding particular characteristics of the locating signal itself. In this connection, at least some investment in operator training is required. Moreover, locating operations are slowed to some extent by requiring the application of procedures which insure accurate locating. These procedures become more important in proportion to the level of inexperience of an unskilled operator.
As one concern, it should be appreciated that in many regions buried lines have previously been installed. When such lines are present, it is important to avoid damage caused by contact with the boring tool. In the past, operators often relied on pre-existing information as to the location of the lines provided, for example, by a utility company or by locating services frequently provided by the utility company using simplistic locating devices and techniques. This concern has been further elevated with the possibility of the presence of fiber optic cables. In many instances, the lines are themselves electrically conductive or, in the case of fiber optic cables, are configured with an electrically conductive tracer wire for use in transmitting a utility locating signal therefrom. It is submitted that a portable unit remains to be seen which facilitates boring tool and cable locating in a single, convenient device.
The present invention provides a highly advantageous portable locator and associated method which is submitted to resolve the foregoing concerns while providing still further advantages.
As will be described in more detail hereinafter, there is disclosed herein a portable locator and associated method for tracking the position of a boring tool and/or one or more buried lines within a region.
In one aspect of the invention, the boring tool is moved through the ground within a given region along a path while transmitting a locating signal such that the locating signal exhibits locate points at the surface of the ground, both ahead of and to the rear of the boring tool. A local flux intensity of the locating signal is measured for at least one above ground point to establish a flux vector at that point which is generally oriented in a horizontal plane. The orientation of the horizontal flux vector within the horizontal plane is used in a predetermined way which, at least to an approximation, limits the possible directions of a nearest one of the locate points relative to the above ground point.
In one feature, the orientation of the flux vector is used in the predetermined way by displaying the orientation to an operator at the above ground point to at least serve as an intermediate step in guiding the operator to the locate point.
In another feature, the orientation of the horizontal flux vector indicates two possible directions of the nearest locate point that are opposing with respect to the above ground point. The horizontal flux vector is used in the predetermined way in combination with a vertical flux intensity of the locating signal that is established at the above ground point from the measured local flux intensity to indicate a single one of the two possible directions as the general direction of the nearest locate point.
In still another feature, with the portable locator in a particular orientation, a positional relationship is displayed on the portable locator including the predicted location of the nearest locate point relative to the portable locator having a directional indication such that the displayed directional indication points in the actual direction of the predicted locate point from the initial above ground point.
In yet another feature, when the orientation of the portable locator at the first above ground point is varied from the particular orientation, the portable locator displays an updated positional relationship such that the directional indication continuously points to the predicted location, irrespective of a predetermined degree of variation of orientation of the portable locator.
In an additional feature, the portable locator is moved iteratively to additional above ground points at which the display is updated so as to indicate additional directional indications. With sufficient iterations, the location of the predicted locate point converges with the actual locate point.
In another aspect of the present invention, a local flux intensity of the locating signal is measured for at least one above ground point to establish a flux vector at that point which is generally oriented in a horizontal plane. An orientation of the flux vector is then displayed to an operator at the above ground point to, at least in part, serve in guiding the operator to at least one of the locate points.
In yet another aspect of the present invention, a boring tool is moved through the ground within a given region along a path while transmitting a locating signal having a transmit axis such that the locating signal exhibits locate points at the surface of the ground, one of the locate points being ahead of the boring tool and the other one of the locate points being to the rear of the boring tool so as define a vertical plane including the transmit axis along with a locate line that is accessible at the surface of the ground and included in a locate plane which extends through the boring tool in a direction normal to the transmit axis. An above ground point is established that is within a side locating region defined between a pair of planes one of which extends through each locate point normal to the transmit axis. A local flux intensity of the locating signal is measured at the above ground point using a portable locator in a particular orientation. Using the local flux intensity, a predicted locate line angular orientation is established which, at least to an approximation, limits the possible directions to and orientations of a predicted locate line relative to the particular orientation of the portable locator at the above ground point.
In one feature, the predicted locate line may be in two possible general, but opposing directions from the above ground point. The predicted locate line angular orientation is used in combination with a vertical flux plane slope of the locating signal, that is established at the above ground point from the measured local flux intensity, to indicate a single one of the two possible general directions as the direction of the predicted locate line.
In another feature, the portable locator is moved iteratively to additional above ground points at which the display is updated so as to indicate additional positions of the predicted locate line. With sufficient iterations, the location of the predicted locate line converges with the actual location of the locate line. In yet another feature, crossing of the locate line is detected based on monitoring a vertical component of the flux intensity of the locating signal.
In still another aspect of the present invention, a first type of positional relationship is displayed to an operator at an above ground point including at least the position of the portable locator and an estimated position of one of a nearest one of the locate points to, at least in part, serve in guiding the operator to at least the nearest locate point using measured values of flux intensity of the locating signal. After finding at least the nearest locate point, the locator is moved in a direction from the nearest locate point into an adjacent side locating region defined between a pair of planes one of which extends through each locate point and each of which is normal to the transmit axis. Based on a set of certain criteria within the adjacent side locating region, as the portable locator is moved therethrough, the portable locator is switched to a locate line display to display a second type of positional relationship including at least the position of the portable locator and an estimated position of the locate line. In one feature, the locate line display is automatically presented based on detection of flux lines produced by the locating signal in a predetermined range of flux slope orientation such that the portable locator is, at least to an approximation, in proximity to the locate line. The predetermined range of flux slope orientation may be determined, at least in part, using a vertical component of the intensity of the locating field.
In an additional aspect of the present invention, a region includes at least one generally straight in-ground cable line extending across the region, from which cable line a locating signal is transmitted. The cable line is located by measuring a local flux intensity of the locating signal at a first above ground point within the region using a portable locator in a particular orientation. Using the local flux intensity, a cable line angular orientation is established which limits the possible directions to the cable line relative to the particular orientation of the portable locator at the above ground point.
In one feature, a vertical flux slope orientation is established at the above ground point and an actual direction of the cable line is selected from the possible directions based on the vertical flux orientation. The cable line is then displayed in a position to the portable locator with the portable locator in its particular orientation.
In another feature, an updated positional relationship is displayed on the portable locator after moving the portable locator into a new particular orientation to continuously indicate, at least to within an approximation, the actual position of the cable line, irrespective of a predetermined degree of variation in orientation of the portable locator.